Auf dem Weg zur “Mechano‐Chemie”: mechanisch induzierte Isomerisierungen von Thiolat‐Goldclustern

Abstract

Cluster auf der Streckbank: Simulationen zufolge können atomare Manipulationstechniken wie die Rasterkraftmikroskopie verwendet werden, um mithilfe verankerter Thiolate aus Goldclustern monoatomare Nanodrähte herzustellen (siehe Bild; Au=gold, S=gelb). Die Isomerisierung der kovalent gebundenen Spezies kann anhand einer Kraft‐Abstands‐Kurve verfolgt werden.

Theoretical Chemistry of Gold

“…Another possibility would be the influence of thiolates 31. 302 The mechanical force on the monoatomic wire can reach about 2 nN before the wire breaks302 and the process could be seen as “mechanochemistry”: feeding in mechanical energy to break a particular chemical bond. Breaking forces of the order of 1–2 nN are commonly obtained 33.…”

Coupling of Mechanical and Chemical Energy: Proton Affinity as a Function of External Force

“…[7] A recent example of mechanochemistry is the mechanically induced isomerization of thiolate-gold clusters. [8] Besides simple homolytic bond breaking, it is conceivable that the application of an external force may also modify the course and outcome of more complex chemical reactions involving multiple reactants. Aktah and Frank showed in a recent study that ether bonds in aqueous solution undergo heterolytic cleavage under mechanical stress.…”

Origins of Material Failure in Siloxane Elastomers from First Principles

“…Understanding these processes entails a full description of the electronic structure of a system during the process of bond rupture and the subsequent reactions between ruptured fragments to correctly determine the underlying chemistry.Information on the response of individual chemical bonds subjected to a tensile load is accessible via single-molecule atomic force microscopy (AFM) experiments, [4][5][6] which can be interpreted with theoretical studies. [7][8][9][10][11][12][13][14][15][16][17][18][19] In the experiments, a single polymer is stretched between a substrate and an AFM tip until one of the backbone bonds ruptures. Factors that can affect the magnitude of the measured rupture force, such as the polymer length and pulling velocity, [15,17] the solvent, [16,18] the presence of knots in the polymer chain, [11,12] and the pulling of a molecule from a substrate, [13,14,19] have been examined by using Car-Parrinello molecular dynamics (CPMD) simulations.…”

“…[7][8][9][10][11][12][13][14][15][16][17][18][19] In the experiments, a single polymer is stretched between a substrate and an AFM tip until one of the backbone bonds ruptures. Factors that can affect the magnitude of the measured rupture force, such as the polymer length and pulling velocity, [15,17] the solvent, [16,18] the presence of knots in the polymer chain, [11,12] and the pulling of a molecule from a substrate, [13,14,19] have been examined by using Car-Parrinello molecular dynamics (CPMD) simulations. These CPMD studies provide valuable insights into the characteristics of bond rupture within single molecules, because a full electronic structure calculation is performed on the fly for a molecular dynamics trajectory, which allows a com-plete description of the stretching of an oligomer in the highforce regime.Of interest in understanding stress-induced material failure in the bulk elastomer is what subsequently happens to the rupture products-in particular, whether chemical reactions between the rupture products lead to permanent weakening of the material or not.…”